It is the purpose of this research proposal to define the mechanisms that regulate intracellular calcium homeostasis in the mammalian growth plate chondrocyte. We will study the effects of parathormone somatomedin, the Vit D matabolites and the local microenvironmental concentration of PO4=, O2 and pH on growth plate chondrocyte calcium transport and homeostasis. It is intended that this information will lead to a better understanding of normal growth plate matrix mineralization and the role of the chondrocyte and their mitochondria in this process. The candidate has completed the equivalent of two years of research at the postdoctoral level. One year has been on a full time basis in the area of growth plate physiology and mitochondrial calcium transport. The other year has been on a part-time basis during the last three years of clinical training in Orthopaedic Surgery. This latter research has been in growth plate chondrocyte physiology and in the area of in vivo scar inhibition using cis hydroxyproline. The University of Pennsylvania is an ideal environment for training in the area of chondrocyte physiology and intracellular calcium homeostasis.